Data units for additive manufacturing

ABSTRACT

In an example, a data unit includes a mounting to removably mount the data unit on a receiving portion of an additive manufacturing build material container, a data source to provide data comprising a plurality of additive manufacturing parameters and a communications interface to communicate with a reader of an additive manufacturing build material processing apparatus. The communications interface is to transmit data from the data source to the additive manufacturing build material processing apparatus.

BACKGROUND

Additive manufacturing techniques such as three-dimensional (3D)printing relate to techniques for making 3D objects of almost any shapefrom a digital 3D model through additive processes in which 3D objectsare generated on a layer-by-layer basis under computer control. A largevariety of additive manufacturing technologies have been developeddiffering in build materials, deposition techniques and processes bywhich the 3D object is formed from the build material. Such techniquesmay range from applying ultraviolet light to photopolymer resin, tomelting semi-crystalline thermoplastic materials in powder form, toelectron-beam melting of metal powders.

Additive manufacturing processes may begin with a digital representationof a 3D object to be manufactured. This digital representation may bevirtually sliced into layers by computer software or may be provided inpre-sliced format. Each layer represents a cross-section of the objectto be manufactured, and is sent to an additive manufacturing apparatus(also termed a “3D printer”) where it is built upon a previously builtlayer. This process is repeated until the object is completed, therebybuilding the object layer-by-layer. While some available technologiesdirectly print material, others use a recoating process to formadditional layers that can then be selectively solidified in order tocreate the new cross-section of the object.

The build material from which the object is manufactured may varydepending on the manufacturing technique and may comprise powdermaterial, paste material, slurry material or liquid material. The buildmaterial is usually provided in a source container from where it needsto be transferred to the building area or building compartment of theadditive manufacturing apparatus where the actual manufacturing takesplace.

DRAWINGS

FIG. 1 is a schematic drawing of an example data unit;

FIG. 2 is another example data unit;

FIG. 3 is an example of build material container;

FIG. 4 is an example of an opening in a build material container;

FIG. 5 is a flowchart of a method of acquiring data from a data source;

FIG. 6 is a schematic representation of example data transfer routes inan additive manufacturing system;

FIG. 7 is a flowchart of a method for exchanging data with a datasource; and

FIG. 8 is a schematic drawing of an example of an additive manufacturingapparatus.

DESCRIPTION

Three-dimensional objects can be generated using additive manufacturingtechniques. The objects may be generated by solidifying portions ofsuccessive layers of build material. The build material can bepowder-based and the properties of generated objects may be dependent onthe type of build material and the type of solidification. In someexamples, solidification of the powder material is enabled using aliquid fusing agent. In further examples, solidification may be enabledby temporary application of energy to the build material. In certainexamples, fusing and/or bind agents are applied to build material,wherein a fusing agent is a material that, when a suitable amount ofenergy is applied to a combination of build material and fusing agent,causes the build material to fuse and solidify. In other examples, otherbuild materials and other methods of solidification may be used. Incertain examples, the build material includes paste material, slurrymaterial or liquid material.

In one example the build material in the source container is powder thathas an average volume-based cross sectional particle diameter size ofbetween approximately 5 and approximately 400 microns, betweenapproximately 10 and approximately 200 microns, between approximately 15and approximately 120 microns or between approximately 20 andapproximately 80 microns. Other examples of suitable, averagevolume-based particle diameter ranges include approximately 5 toapproximately 80, or approximately 5 to approximately 35 microns. Inthis disclosure a volume-based particle size is the size of a spherethat has the same volume as the powder particle. With “average” it isintended to imply that most of the volume-based particle sizes in thecontainer are of the mentioned size or size range but that the containermay also contain particles of diameters outside of the mentioned range.For example, the particle sizes may be chosen to facilitate distributingbuild material layers having thicknesses of between approximately 10 andapproximately 500 microns, or between approximately 10 and approximately200 microns, or between approximately 15 and approximately 150 microns.One example of an additive manufacturing system may be pre-set todistribute build material layers of approximately 90 microns using buildmaterial containers that contain powder having average volume-basedparticle diameters of between approximately 40 and approximately 60microns. For example the additive manufacturing apparatus can be resetto distribute different layer thicknesses.

Suitable powder-based build materials for the container of thisdisclosure include at least one of polymers, crystalline plastics,semi-crystalline plastics, polyethylene (PE), polylactic acid (PLA),acrylonitrile butadiene styrene (ABS), amorphous plastics, PolyvinylAlcohol Plastic (PVA), Polyamide, thermo(setting) plastics, resins,transparent powders, colored powders, metal powder, ceramics powder suchas for example glass particles, and/or a combination of at least two ofthese or other materials wherein such combination may include differentparticles each of different materials or different materials in a singlecompound particle. Examples of blended build materials include alumide,which may include a blend of aluminum and polyamide, multi-color powder,and plastics/ceramics blends.

In additive manufacturing, it may be the case that build materialsbecome heated. For example, where fusing agents are applied and causedto absorb energy, this tends to heat the build material, in particularin the regions to which fusing agents have been applied. In addition,some additive manufacturing processes may pre-heat build materials, ormay comprise exothermic chemical reactions or the like. In suchprocesses, there is a possibility of build material overheating, forexample to the point where it could damage apparatus or even ignite.

Different build materials may be associated with different processingtemperatures. For example, different materials may have differentmelting points, or different flash points (the flash point is thetemperature at which a build material may evaporate to such an extentthat the vapour may ignite). In addition, different temperatures mayresult in different physical properties of an object, such as objectstrength, resilience, appearance or the like.

A particular additive manufacturing apparatus may be intended to be usedwith a range of such materials and therefore may comprise settings(temperature settings, layer processing times, etc.) which are matchedto the build material being processed thereby. If too high a temperatureis reached during object generation for a particular build material,there are risks, which may include an object failing to be manufacturedas intended, damage to equipment, and/or the possibility of explosionsand/or fire. In some examples, the additive manufacturing apparatus maybe arranged for operation with a particular build material or rangethereof, and attempting to manufacture an object using a different buildmaterial may result in similar risks.

In addition to considering careful handling of individual buildmaterials, consideration may be made in relation to mixtures of buildmaterial, even at a trace level. For example, a poorly consideredmixture may result in failure to manufacture an object as intended, asdifferent melting temperatures may mean that some material within themixture melts and other does not, or some material may overheat. Inother examples, the object may have unintended properties as a result ofa poorly considered mixture. Moreover, different build materials mayreact adversely with one another, for example when heat is applied (forexample, when the build material is molten or in a vapour state). Again,there may be risks of damage to apparatus, infrastructure or personnel.

In examples set out herein, a supply of build material may be associatedwith a data source providing at least one additive manufacturingparameter, which may be or include a build material parameter (e.g.describing an aspect or attribute of the build material), or anauthorisation parameter, which may play a part in an ‘authorisation toprint’ operation, for example unlocking an additive manufacturingapparatus for use. In some examples, the association between the datasource and the supply may be a physical association, for example a datasource such as a solid state memory may be attached to a container inwhich the build material is transported. However, even if the buildmaterial is physically or otherwise associated with a supply of buildmaterial, it may that counterfeit or uncontrolled sources of buildmaterial are available. Thus, in some examples set out herein, thesource of the data and/or the data source is verifiable such that a usermay be confident that the build material is from a trusted source and,where build material parameters are provided, the user may be confidentthat the build material is as described by the build materialparameter(s).

FIG. 1 shows an example of a data unit 100. The data unit 100 may be aportable and/or standalone data unit, for example being readilytransportable by hand. The data unit 100 may for example comprise a‘smart card’, and/or have dimensions, at least in a portion thereof,corresponding to the dimensions of a Universal Integrated Circuit Card(UICC), also known as a subscriber identity module, or SIM card. Thedata unit 100 of FIG. 1 comprises a mounting 102, the mounting 102 beingto removably mount the data unit 100 on a receiving portion of anadditive manufacturing build material container. In some examples, themounting 102 may for example have a shape or dimension which iscomplementary to a shape or feature of the receiving portion. In otherexamples, the mounting 102 may comprise features which adhere to,interact with, or interlock with, features of the receiving portion. Themounting 102 may provide a platform for, or may enclose, othercomponents of the data unit 100. The mounting 102 may also provide foreasy handling of the data unit, in some examples providing a portionwhich may be readily held in a user's hand.

The data unit 100 further comprises a data source 104, in this example amemory which is to store a plurality of additive manufacturingparameters, examples of which are described in greater detail below. Thememory 104 may for example comprise non-volatile memory, such as atleast one of read-only memory (ROM, or erasable programmable ROM,EPROM), flash memory, ferroelectric RAM (F-RAM), magnetic memory,optical memory or the like. In some examples, the memory 104 may storedata for a prolonged period. In other examples, the memory 104 may befor temporary storage of data, for example following generation thereofin response to a request for data.

The data unit 100 further comprises a communications interface 106 tocommunicate with a reader of an additive manufacturing build materialprocessing apparatus. For example, such apparatus may be an additivemanufacturing apparatus or ‘3D printer’ which fabricates an object in alayer wise manner, or may be build material treatment apparatus, such asa build material mixing apparatus, or some other apparatus for use inadditive manufacturing. In some examples, the communications interface106 may comprise a galvanic interface, i.e. an electrical connection ismade over which data may be sent or received. In other example, thecommunications interface 106 may operate using ‘wireless’ communicationmethods, such as radio or optical transmission methods. Data from thememory 104 may be transmitted to the additive manufacturing buildmaterial processing apparatus by the communications interface 106. Thecommunications interface 106 may be to communicate with at least twoclasses of additive manufacturing build material processing apparatus,for example with both of additive manufacturing apparatus and buildmaterial treatment apparatus.

As the data unit 100 is provided with a mounting 102 which may beremovably mounted on a build material container, it may be either readin situ on a build material container, or removed therefrom for reading.For example, when in situ on the build material container, it may beread using a reader which is brought into proximity therewith. In someexamples, the reader may be provided in a build material extractionelement, as described below. However, as the data unit 100 may beremoved from the build material container, it may be communicablycoupled with other reader apparatus. For example, the data unit 100could be placed in a reader slot or drive, or brought into proximitywith a proximity reader or the like. This means that the content of thedata unit 100 may be accessed in different ways and by differentapparatus, which in turn eases the specifications for an end user tohave a particular reader apparatus.

To consider an example in which a reader is provided in an extractionelement such as an aspiration, or vacuum, tube and is intended tocommunicate with the data unit 100 in situ, this allows for ease ofhandling of the build material and for transfer of information from thedata unit 100. However, it may be the case that additive manufacturingapparatus could be operated in the absence of such an extraction element(of using an extraction element which does not include a reader). Inthat case, as the data unit 100 is arranged to be removably mounted, itmay be removed from the build material container and read in analternative fashion. This increases the options for accessing the datathereon (which, as noted above, may enhance safety by correctlyidentifying build materials or attributes thereof, or providingauthentication of the source of the build material and/or data content).For example, a user could convey a data unit 100 to alternative readerapparatus, such as a card slot on an additive manufacturing apparatus.

It may also be noted that build material containers may be bulky, andthe contents thereof may be relatively costly. By providing a separabledata unit 100, the whole container need not be moved to access the datain some examples, and a faulty data unit 100 may be replaced withreplacing the entire build material container (and in some examples, itscontent).

In some examples, the data unit mounting 102 may be adapted fortool-less insertion and/or removal from a build material container. Thisincreases the flexibility of the data unit 100 as it may be added toand/or removed from a build material container without any tools (andthus may for example be easily removed or added by an end user).

The additive manufacturing parameters stored in the memory 104 maycomprise authentication data. The authentication data may be for use inauthentication of the build material and/or the data stored in thememory. In some examples, the authentication data may allow the dataunit 100 to authenticate other apparatus or data sources, for example anadditive manufacturing apparatus with which it is in communication. Forexample, the memory 104 may be provided with a key, or a password, foruse in authentication.

The additive manufacturing parameters stored in the memory 104 maycomprise build material identification data. For example, this maycomprise an identification of the material, class of material, particlesize, range of particle sizes, origin (for example, supplier, country oforigin, factory of origin) or the like.

In some examples, the additive manufacturing parameters may comprisebuild material processing parameters, for example temperatures, speedsor other conditions of processing.

In some examples, the additive manufacturing parameters may comprisecompatible build material identification data. Compatible may mean thatthe build materials can be mixed and an object successfully (and/orsafely) generated therefrom. For example, a particular plastic buildmaterial may be compatible with itself and a range of other plastics(for example, a build material may be compatible with, or belong to, atleast one compatible ‘family’ of materials). However, the plastic may beincompatible with other plastics, or with other classes of material suchas at least one rubber. Compatible and/or incompatible materials couldbe explicitly listed. Providing a list in this manner may allow anadditive manufacturing processing apparatus to learn the compatibilityof new build materials.

In some examples, a mixture may be formed deliberately. For example, anobject may be generated from build material comprising a proportion ofbuild material from a plurality of sources, which may include at leastone source build material container and/or at least one recycled buildmaterial source. However, in other examples, at least one build materialmay be present in small amounts, for example trace amounts may remain inan apparatus from a previous processing activity.

In some examples, the parameters may comprise mixing percentage ranges,for example a maximum or minimum proportion of recycled build material,or of build material of a particular type, or the like. In someexamples, the number of generation cycles for which build material hasbeen, or may be, used may be stored as a parameter. In some examples,the parameters may be indicative of at least one, or any combination ofthe following parameters (with example units), each for example beingstored in a memory field.

Name Units Peak Temperature of Melting ° C. Onset temperature of MeltingPeak ° C. Extrapolated onset temperature of Melting Peak ° C. Onsettemperature of Melting Peak ° C. Melting Enthalpy KJ/Kg Peak temperatureof Recrystallization ° C. Onset temperature of Recrystallization Peak °C. Extrapolated Onset temperature of Recrystallization Peak ° C. GlassTransition Temperature ° C. Vicat Softening Temperature ° C. Absorptioncoefficient @ 1500° K color temperature % Absorption coefficient @ 3000°K color temperature % Color (yellow index) Index Emissivity coefficientat Melt Temperature % Particle size - 10 percentile um Particle size -50 percentile um Particle size - 90 percentile um Powder density (loose)g/cm³ Powder density (tapped) g/cm³ Melt flow index cc/10 min Melt flowtemperature ° C. Base Material Density g/cm³ Solution Viscosity NumberSolution Viscosity (Solvent Name) 10 chars Solution Viscosity (SolventTemp) ° C. Base Material Specific Heat KJ/(Kg K) Compatible families(multiple occurrences) 10 chars Thermal Conductivity W/(m K) SpecificHeat KJ/(Kg K) Median Avalanche Angle @ ambient Temperature Deg MedianAvalanche Angle @ spread Temperature Deg Material Flow Function Constantg/cm² Material Flow Function Exponent Number Effective angle of Internalfriction Deg Wall Friction Number White Powder Transmission depth at2750 K source mm Minimum Ignition Temperature dust cloud ° C. MinimumIgnition temperature powder layer ° C. Minimum Explosion Concentrationgr/m³ Minimum ignition energy dust cloud mJ Dust Explosion Class bar m/sMax explosion pressure bar Combustion index Number Maximum recycledpowder mix % Number of Generation cycles Number Water absorption %

These example parameters include processing parameters, material flowparameters and safety parameters. In some examples, the additivemanufacturing parameters may be stored in the memory as a compressed XMLfile. For example, such a file may be an indexed file, and the date maybe recoverable by a reader with access to a dictionary. In otherexamples, XML compressors such as XMill, XGRind, Xpress, XComp or thelike may be used.

FIG. 2 shows an example of a data unit 100′, in which the memory 104 andcommunications interface 106 are mounted on a portion of the mounting102 having dimensions corresponding to the dimensions of a UniversalIntegrated Circuit Card (UICC) (for example, a SIM, MicroSIM or NanoSIMcard). In this example, circuitry is mounted on a portion of themounting 102 which comprises a cut-off corner, which is an orientationfeature as may be seen in a SIM card.

The mounting 102 comprises a circuitry portion 202 on which the memory104 and communications interface 106 are mounted (shown in dotted lineas they are provided on the obscured face of the mounting 102) and aregistration portion 204, the registration portion 204 being to bereceived in a corresponding guide portion of the receiving portion of anadditive manufacturing build material container. For example, thereceiving portion may have a slot-like form, and the registrationportion 204 may have dimensions which are slightly smaller than thewidth of the slot. This may serve to secure and/or position the dataunit 100′ in the receiving portion.

The communications interface 106 is arranged to communicate with areader of an additive manufacturing build material processing apparatus.For example, this may be an additive manufacturing apparatus or ‘3Dprinter’ which fabricates an object in a layer wise manner, or may bebuild material treatment apparatus, such as a build material mixingapparatus, or some other apparatus for use in additive manufacturing. Insome examples, the communications interface 106 may comprise a galvanicinterface, i.e. an electrical connection is made over which data may besent or received. In some examples, the memory 104 and communicationsinterface 106 may operate using ‘wireless’ communication methods, suchas radio or optical transmission methods. Data from the memory 104 maybe transmitted to an additive manufacturing apparatus by thecommunications interface 106

In this example, the data unit 100′ further comprises an authenticationmodule 206. The authentication module 206 may for example comprise atleast one processor and may be arranged to receive an authenticationrequest from an additive manufacturing build material processingapparatus (for example, received via the communications interface 106)and to provide an authentication response for communication to theadditive manufacturing build material processing apparatus. Thisauthentication may be based on an additive manufacturing parameterstored in the memory 104, for example a cryptographic secret code orpassword of the like.

Thus, the authentication module 206 may provide an additivemanufacturing build material processing apparatus with validation of thesource of the build material and/or other additive manufacturingparameters via the communications interface 106. The additivemanufacturing build material processing apparatus may then (in someexamples, on completion of checking of the validity of theauthentication response) trust the content of validated data. As thedata unit 100′ may be associated with a particular source of buildmaterial, for example being provided on or in a build materialcontainer, once the authentication response is verified, it may be thatthe associated build material is also considered to be verified and thesubsequent processing thereof can be conducted with confidence that boththe data and the build material itself are from a trusted source.

For example, the authentication module 206 may be arranged to receive anauthentication request from an additive manufacturing build materialprocessing apparatus comprising a message, to encrypt the message (forexample using a key issued thereto at manufacture) and provide anauthentication response which includes the encrypted message. The buildmaterial processing apparatus may know the key (for example, all or anumber of the instances of data units 100′ may be provided with the samekey, or a one of a limited number of keys), or may be able to derive thekey based on, for example, another portion of the message. By sendingthe encrypted message, the data unit 100′ proves that it has access tothe key, and, as long as it can be trusted that the key has beendistributed in a secure manner, this authenticates the identity of thedata unit 100′. In other examples, other authentication methods may beused.

The authentication response may comprise at least part of a release codefor the additive manufacturing build material processing apparatus, therelease code being to authorize at least one additive manufacturingprocess of the additive manufacturing build material processingapparatus. For example, the release code may comprise a ‘right to print’authorization, which allows an additive manufacturing apparatus to printan object (in some cases conditional on attributes of the object, suchas the volume or material property specifications being reproducibleusing the build material associated with the data unit 100′, or on anadditive manufacturing apparatus being suitable to process the buildmaterial, or there being sufficient or appropriate build materialavailable for a particular additive manufacturing task, or the like).

In some examples, the authentication may be two-way, i.e., theauthentication module 206 may authenticate the additive manufacturingbuild material processing apparatus, for example based on the requestreceived therefrom. It may be, for example, that data is not transmittedto the additive manufacturing build material processing apparatus unlessthe request is authenticated. In some examples, it may be that anauthentication response is not transmitted unless the request isauthenticated. Such authentication may for example use a shared secretand/or a digital signature or the like.

In this example, at least some additive manufacturing parameters arestored in an encrypted form and the data unit 100′ comprises a datasecurity module 208, which may decrypt the data before transmission toan additive manufacturing build material processing apparatus. In someexamples, the data may be (re)encrypted prior to transmission, forexample based on a session key established following authentication, orusing a public key of the build material processing apparatus.

In some examples, at least some portions of the memory 104 are writable.In some such examples, the communications interface 106 may be arrangedto receive data and to write the data to the memory 104. For example,this may be data relating to at least one of the plurality of additivemanufacturing parameters. In some examples, the memory 104 may comprisesa plurality of data fields and at least some data fields of the memory104 may be associated with a condition. In such examples, the data to bewritten to the memory 104 may be associated with a validity check. Forexample, it may be case that a certain data field relates to the volumeof build material in a container (which may, in some examples, bedispensed in a metered manner), and the container is not to be refilled.In such an example, it may be that field may be decremented, i.e. thevalue therein may reduce, but not increase. In such an example, aprocessing module of the data source may verify that the data meets thecriteria before allowing the data field to be overwritten. In someexamples, certain data fields may be written to ‘read-only’ data fields.This can be a function of the memory 104 itself (i.e. there may be noway of rewriting the memory) or may be controlled by a processingmodule. Other data fields may be rewritten once, or until a data fieldis locked, (for example, to identify the build material processingapparatus which uses the build material associated therewith), andthereafter become read-only data fields. Other data fields may beassociated with a token, for example comprising one or more bits whichmay be flipped from a 0 to a 1. In some examples, the token may bechanged just once. Other data fields may be read and written to onseveral occasions.

In some examples, the authentication module 206 may verify at least oneof the additive manufacturing build material processing apparatus andthe data content prior to writing the data to the memory 104. In someexamples, locally generated data, for example determined by a processorof data unit 100′ may be written the memory 104.

In some examples, the memory 104 may be written with data to the effectthat the data unit 100′ will not authorise a subsequent read operationand/or build material processing operation. For example, data may bewritten to the effect that the build material is exhausted (e.g. a fieldrelating to the volume of the build material may be set to zero, orempty). In another example, a key used for authentication may beoverwritten or deleted such that the build material can no longer beauthenticated. In another example, the memory may be cleared oroverwritten (for example scrambled), or a flag may be set indicatingthat the data has been accessed.

Such measures may mean that the data unit 100′ is prevented fromproviding a subsequent authorisation to print. This may for example beuseful in preventing an attempt to circumvent the security provided bythe data unit 100′ by reusing the data unit 100′ with build materialfrom multiple containers. Unless a preventative measure is taken, thiscould result in false authorisation of build material and/or falseauthentication of data. However, by taking action to prevent reuse ofthe data unit 100′, the risks of such circumvention are reduced.

In some examples, at least a portion of the memory 104 could be writtenor rewritten with parameters ‘on the fly’, i.e. parameters may begenerated for substantially immediate transmission to additivemanufacturing build material processing apparatus. For example, a volumeof build material may be determined based on a measurement of a volumeor weight of build material in the container made in response to arequest for parameters, passed to memory (for example on a transientbasis) and transmitted to an additive manufacturing build materialprocessing apparatus. In such examples, the memory 104 may comprise, atleast in part, a transient memory, an ‘overlay’ memory, a data cacheand/or a memory buffer, or the like, in which parameters are stored on ashort term basis. However, such parameters may also be generatedfollowing a request and stored in a persistent manner, or untilover-written.

The mounting 102 of FIG. 2 comprises a compressible element 210, in thisexample comprising a region of the mounting 102 separated from a bodythereof by a pair of slots. It may be noted that this compressibleelement 210 comprises two arms which bow outwards, and may be caused tobend inwards, closing the slots by pressing the compressible element 210against a rigid element, which may be provided on a build materialcontainer. The maximal longitudinal length of mounting in this plane isdefined by the positions of the arms. When the arms are flexed towardsthe body of the mounting 102, the compressible element 210 is compressedand this reduces the longitudinal dimension of the mounting 102 in thisplane. However, this dimension could be reduced in some other way, forexample by providing a telescoping portion, or a concertina portion, orthe like and therefore this is just one example of a compressibleelement 210. The compressible element 210 is resilient, such that theslots will open unless pressure is applied thereto. This may assist inlocating the mounting 102 within a receiving portion of a build materialcontainer. In some examples, the mounting 102 may be configured suchthat a user may compress the compressible element 210 without amechanical advantage or a tool. This may allow tool-less insertionand/or removal of the mounting 102.

The mounting 102 further comprises a retaining feature 214 forinteracting with a build container, in this example comprising a tongue,which is arranged to interact with a retaining projection 406 of thebuild material container. The mounting 102 further comprises a tab 216,which is positioned so as to be holdable by a user in inserting or thedata unit 100′ into a receiving portion of a build material container,or removing the data unit 100′ thereform.

The retaining feature 214 may be plastically deformable, i.e.deformation thereof is at least partially irreversible. There may besome elastic deformation of the retaining feature 214, but beyond athreshold stress (which may be less than the pressure applied remove adata unit 100 from the build material container), the deformation may bepermanent (for example, the retaining feature 214 may snap or break) orotherwise apparent from inspection of the mounting 102. This may reducethe reusability of a data unit 100′, and may provide a tamper evidentfeature. In some examples, deformation of the retaining feature 214 mayoccur in preference to other portions of the data unit mounting 102. Forexample, the retaining feature may be relatively weaker (for example,more readily bent or broken) than the circuitry portion 202. This maymean that circuitry (in this example, the memory 104 and communicationsinterface 106) is mounted is mounted on a portion which is unlikely tobend or flex under normal manipulation of the data unit 100′, and maytherefore be protected from damage which could be caused by suchbending.

In some examples, the mounting 102 may be configured such that a usermay deform, or break, the retaining feature 214 without a mechanicaladvantage or a tool. This may allow tool-less insertion of the mounting102.

The data unit mounting 102 may comprise, in whole or in part, a plasticmaterial. As such, the mounting 102 may be relatively low cost. The dataunit mounting 102 may be a plastic, monolithic component. In someexamples, the data unit mounting 102 may comprise, in whole or in part,a conductive plastic material. In order to prevent a build-up of staticenergy, conductive components may be used to couple the build materialcontainer to other apparatus. Providing a conductive mountingcontributes to the electrical coupling. In other examples,non-conductive mountings may be provided. In some examples, the mountingmay be conductive, but comprise a different material, such as anelectrically insulating plastic bearing metal tracks, or be formed ofmetal or the like. By providing a separable mounting 102, the conductiveproperties of a data unit 100. 100′ may be designed separately to theconductive properties of any other aspect of the build materialcontainer, which may reduce compromise in design. For example, in orderto function with particular read apparatus (for example, to mitigateinterference or the like), it may be that any circuitry may beelectrically isolated by providing an electrically isolating mounting102. Therefore, in some examples, the mounting 102 may comprise adifferent material, or have different material properties, to a buildmaterial container in which it is mounted.

As is shown in FIG. 2, the data unit mounting 102 may comprise a firstplanar portion and a second planar portion, the planar portions beingsubstantially orthogonal. In an example, the planar portions may beconnected substantially along a shared edge. The circuitry region may beon the first planar portion, and the second planar portion may provide a‘stop’ surface when the first planar portion is inserted into a reader,and may ensure that the data unit 100′ at least partially remainsoutside such a reader.

FIG. 3 shows an example of a container 300 comprising a data unit 100′and a storage volume 302 to contain additive manufacturing buildmaterial. In some examples, the container 300 may contain a buildmaterial. In this example, the data unit 100′ is situated in the regionof an opening 304 in the container 300, in particular in a neck thereof.The build material container further comprises a storage volume 302 tocontain additive manufacturing build material.

In one example the container 300 may contain a source supply of freshbuild material. In another example the container 300 is a source supplyof recycled or partly recycled build material. In yet another examplethe container 300 may be used, at least temporarily, as a buffer supply.

The storage volume 302 may comprise a reservoir to hold build material.In some examples, the storage volume 302 may include an upper uprightsection having relatively upright side walls, at least in a filledstate, along most of the height of the reservoir, a lower funnel havingconverging side walls; and a build material outlet structure providingthe opening to allow build material to exit the reservoir. The reservoirmay comprise, or be lined with, a flexible material such that, whenbuild material is removed therefrom (for example under a negativepressure), the volume of the reservoir may decrease. The reservoir maybe contained in a rigid or semi rigid supporting structure which doesnot deform.

In some examples, the data unit 100′ may be arranged in the opening suchthat when an extraction element is attached thereto, a memory reader inthe extraction element may read the data unit 100′. In some examples,the extraction element may be at least temporarily attached to theopening based on its orientation (e.g., there may be a locked or fixedorientation and unlocked orientation). In such examples, the lockedorientation may be an orientation in which the reader is proximate to,or interlinked with, the data unit 100′.

FIG. 4 shows, in cross section, an example of an opening 402 in a buildmaterial container. As can been seen, the registration portion 204 ofthe mounting 102 is received within a slot 404, which locates the dataunit 100′ in a predetermined position (for example, a position in whichit can be read by a reader). A retaining projection 406 is arranged tointeract with the securing feature 214. When the data unit 100′ isplaced into the opening 402, the compressible element 210 may be urgedagainst a portion of the opening which curves in the opposite directionto the bow of the compressible element 210. This closes the slots. Thesecuring feature 214 may also flex then resiliently straighten so as tobe held in place by the projection 406. The compressible element 210then urges the securing feature so as to be retained by the projection406. In this example, the data unit 100′ can be removed from the openingby urging it towards the centre of the opening 402. This may cause thesecuring feature 214 to bend or even break away, and the material in theregion of the compressible element 210 may also bend or break (forexample, at the narrowed portion defined between the slots), so as torelease the data unit 100′ from the opening 402.

In this example, an outlet structure 408 is arranged in the opening 402.The outlet structure 408 in this example comprises a retaining structureto maintain a connection to a connecting build material extractionelement such as an aspiration tube which may be used to draw buildmaterial from the reservoir in to a build material processing apparatus.In particular, the outlet structure 408 comprises an adaptor 410 toguide an external aspiration system in connection with the outletstructure 408, the adaptor comprising an interface face 412 around itsoutlet opening, the interface face 412 extending perpendicular to anaspiration direction, and a standing circumferential wall 414 withinwhich an aspiration tube is to be inserted to engage the interface face412. In some examples, the outlet structure 408 may include a collectstructure to collect build material from the bottom and guide the buildmaterial to an outlet opening at the top. For example, this may be atube (which may be rigid tube) which extends to the lower portions ofthe reservoir.

FIG. 5 is an example of a method comprising, in block 502, acquiring, atan additive manufacturing apparatus, a supply of build material foradditive manufacturing. Block 504 comprises determining, from aplurality of possible data sources, an available data source comprisingadditive manufacturing parameters, and block 506 comprises receivingdata from the available data source.

This method therefore allows additive manufacturing parameters (whichmay be build material parameters and/or build authorisation parameters)to be retrieved from a plurality of sources.

For example, the data source may comprise a data unit 100, 100′ or thedata source may be provided as part of a transfer vessel.

An example of a system of apparatus is shown in FIG. 6. In this example,there are two routes for validation, authorisation and/or buildparameters to be transferred from an initial data source, which may beprovided as a data unit 100, 100′ supplied on a build material container300, to an additive manufacturing apparatus 606. For example, it may bethe case that the build material is processed (for example, mixed withother sources of build material) in a first apparatus 602, transferredto a transfer vessel 604 and transported to a second apparatus 606 forobject generation. In such an example, the data from a data unit 100,100′ may be read therefrom by the first apparatus 602, and transferredto a memory 608 of the transfer vessel 604. In such examples, the secondapparatus 606 (i.e. the additive manufacturing apparatus) may be able toread the data directly from the memory of the transfer vessel 604, i.e.the data source may be provided on the transfer vessel 604. In otherexamples, the second apparatus 606 may be in communication with thefirst apparatus 602, which may therefore provide a data source. However,in some examples, a user may not own or operate the first apparatus 602.In such an example, the user may instead detach the data unit 100, 100′from a build material container 300 and provide the data unit 100, 100′to, for example, a card reader of the additive manufacturing apparatus606. In such an example, the data unit 100, 100′ may provide a datasource which is directly available to the additive manufacturingapparatus 606.

In the example of FIG. 6, there is therefore a first data route 610 anda second data route 612.

In the first data route 610, the data unit 100, 100′ is read by a readerin an extraction tube of the first apparatus 602, which in this exampleis a build material mixing apparatus. The build material may performauthentication and/or validation. The build material mixing apparatusthen passes data onto the transfer vessel 604, specifically into thememory 608 thereof. In order to maintain security, this data may besigned or encrypted or the like so as to be authenticable by theadditive manufacturing apparatus 606. This data may include the data asread from the data unit 100, 100′ and/or other data. For example, thebuild material mixing apparatus may fill a single transfer vessel 604with build material from more than one source, and may include data inrelation to the build materials mixed, the mixing proportions and thelike. The build material mixing apparatus may also write data to thedata unit 100, 100′, for example how much build material has beenremoved therefrom.

The transfer vessel 604, which in this example is a trolley, is thentransferred (i.e. physically moved) to the additive manufacturingapparatus 606, which may then read the memory 608, and acquirevalidation, authentication and/or build parameters and the like. Thus,in the example of the first data route 610, the additive manufacturingapparatus may be provided with an authorisation and/or additivemanufacturing data via the transfer vessel 604, which may itselfacquires data from a pre-treatment apparatus. As such, the parametersand/or the (at least implicit) authorisation travel with the buildmaterial to which they pertain, providing for ease of use and/orsecurity enhancements as the parameters/authorisation may beconsistently associated with the correct build material.

In the second data route 612, the data unit 100, 100′ is separated fromthe build material container 300, and passed directly to the additivemanufacturing apparatus 606. The additive manufacturing apparatus 606may then acquire validation, authentication and/or build parameters andthe like directly from the data unit 100, 100′. In such an example,build material may for example be tipped into the transfer vessel 604from the build material container 300, and the transfer vessel 604coupled to the additive manufacturing apparatus 606. In such examples,the memory 608 may not contain data, or may not contain authorised orverifiable (for example, by validation) data. In some examples,obtaining access to the interior of the transfer vessel 604, for exampleto manually tip the content of a build material container into thetransfer vessel 604, may cause the memory 608 to be blanked, or writtenwith data indicating that any memory content thereof is not suitable forproviding additive manufacturing parameters in relation to the buildmaterial contained therein.

In other examples, there may be other data sources, for example aninternet connection to a remote data source, or a proximity reader, awired or wireless communication between the first and second apparatus,an extraction element of the second apparatus or the like. Byconsidering multiple data sources, additive manufacturing parameters maybe provided to the additive manufacturing build material processingapparatus in a plurality of ways, and the versatility of the apparatusmay be increased.

FIG. 7 provides an example of another method, comprising block 502 asdescribed in relation to FIG. 5. Blocks 702 and 704 are an example ofdetermining an available data source as described in relation to block504 above. In block 702, the additive manufacturing apparatusdetermines, via a communication link (which may be wired or wireless,for example comprising an optical or radio communications link), if theadditive manufacturing parameters are available from a memory of asupply vessel containing the build material. This may for examplecomprise determining if the memory thereof contains data. In someexample, it may be verified that the data is at least one of: authoriseddata, data written thereto within a time-out window, data which may bevalidated by the additive manufacturing apparatus or the like. If not,the method comprises, in block 704, determining if the additivemanufacturing parameters are available from a memory provided to areader of the additive manufacturing apparatus. Determining that thedata source is available may comprise determining that a data source hasbeen presented to the reader, and, in some examples, validating the datathereon. If no data source is available, the method may terminate. Oncea data source has been determined, data may be received from theavailable data source. Blocks 706 and 708 are an example of receivingdata as described in relation to block 506 above. In this example, thedata comprises, in block 706, a build material processing authorization,wherein a validity of the build material processing authorization isverifiable by the additive manufacturing apparatus. This may for examplecomprise verification of a digital signature, or verification based onencryption, or the like. It may be noted therefore that the methodprovides for a plurality of data sources which may provide anauthorisation.

Block 708 comprises receiving at least one additive manufacturing buildmaterial parameter from the available data source. For example, thesemay specify at least one processing parameter such as a processingtemperature. For examples in which compatibility parameters are includedin the build material parameters, this may comprise considering if thebuild material is compatible with the apparatus, or with build materialpreviously used in the apparatus (for example, build materials usedsince a cleaning cycle). Block 710 comprises processing the buildmaterial by the additive manufacturing apparatus according to thetransmitted at least one additive manufacturing build materialparameter. In some examples, processing the build material by theadditive manufacturing apparatus may comprise rejecting the buildmaterial, for example on the basis that it is incompatible with theadditive manufacturing apparatus (or with the additive manufacturingapparatus in a given state). This may therefore enhance safety, as thebuild material will be processed if compatible and/or according toparameters provided by the data source.

Block 712 comprises writing, to the available data source, an indicationthat the data thereon has been read. In some examples, the data to bewritten may depend on the data source. For example, if the data sourceis a portable data unit (for example a data unit 100, 100′), writing, tothe available data source, an indication that the data thereon has beenread may set a volume of build material remaining to be none, or may seta flag or revoke a key. This may result in the ability of the datasource to authenticate or allow object generation processes to carriedout in a manner authorised thereby being revoked, which may be usefulwhere the amount of build material dispensed is unmetered. However, ifthe data source is a memory of a transport apparatus, the data sourcemay be written with an indication of how much build material has beenused, or other data associated with the processing of the buildmaterial, such as temperatures, fusing agents or other print agents, anidentification of the apparatus used to perform the processing or thelike.

FIG. 8 is an example of an additive manufacturing apparatus 800comprising a first interface 802 and second interface 804. Both thefirst and second interfaces 802, 804 are to receive data associated witha build material. The first interface 802 is to receive data from afirst data source. In the example of the Figures, this is a data sourceassociated with a memory 806 of a build material transport apparatus808. The second interface 804 comprises a reader to receive data from aportable data unit. In this example, the reader comprises an opening toreceive at least part of the portable data unit, which may be portablein the sense of being a standalone unit of non-volatile memory, whichcan be held or carried. In some examples, the portable data unit maycomprise a memory card, such as a UICC or the like. In some examples,the portable data unit may be a data unit 100, 100′ as described above.

In some examples, the first interface 802 may be an interface to receivedata from a memory which is associated (for example, physicallyassociated) with a source of build material. For example, the firstinterface 802 may be to interface with a memory which is mounted on orin a build material vessel (which may be a trolley or may be a buildmaterial container, or any other vessel for build material). In someexamples, the first data source may comprise at least part of anyapparatus which has received data, directly or indirectly, from aportable data unit, and the first interface 802 may be an interface toreceive data from such a data source.

The additive manufacturing apparatus 800 further comprises a controlmodule 810 to control object generation based at least in part on thereceived data. For example, the data may comprise data authorising aprint activity, or validating the source of build material, or maycomprise at least one setting for the manufacturing process (or dataallowing at least one setting to be determined).

In this example, the additive manufacturing apparatus 800 is arranged toreceive the transport apparatus 808, which comprises a trolley, andwhich provides a print bed, but in other examples, the build materialmay be transferred from the transport apparatus to the additivemanufacturing apparatus 800 in another manner, for example via a hose orthe like. In such examples the first interface 802 may be provided onthe hose, or on other apparatus through which build material isreceived.

The control module 810 may determine which interface 802, 804 is incommunication with an available data source, and may receive data fromthe available data source via the associated interface. For example, thecontrol module 810 may carry out the method of blocks 504 and 506 orblocks 702 to 712 above.

In some examples, the control module 810 of the additive manufacturingapparatus 800 may validate a data source. This may for example compriseverifying a digital signature, or carrying out a cryptographic messageexchange or the like. The validation may for example be associated witha time limit, for example, unless the build material is presented withina time window, the validation may expire. In some examples, where thedata source is a transport apparatus, an initial validation may becarried out by another build material processing apparatus, for examplea build material mixing apparatus or the like, which may be the buildmaterial processing apparatus which initially receives the buildmaterial from a build material container. Such an apparatus maydigitally sign data which is written to the memory of the transportapparatus, and validation by the control module 810 may comprisevalidation of the signature. Where the data source is a portable datasource such as a data unit 100, 100′, authentication may be carried outwith an authentication module 206 thereof, as described above. In someexamples, such validation may be carried out in order to determine whichdata source is an available data source for additive manufacturingparameters—i.e. in some examples, a data source may be validated inorder to be considered available.

In some examples, the control module 810 of the additive manufacturingapparatus 800 may receive, from the data source, at least onecompatibility indicator of the build material. This may be used todetermine if the build material meets predetermined compatibilitycriteria. The compatibility criteria may relate to mixtures of buildmaterials (for example, whether the additive manufacturing apparatus hasbeen used to process an incompatible build material, and may contain atleast trace amounts thereof to an extent that proceeding with objectgeneration may be dangerous or likely to be impaired), or the capabilityof the additive manufacturing apparatus to provide processing conditionssuch as temperatures and the like specified in the additivemanufacturing parameters. In some examples, the compatibility criteriamay be based, at least in part, on a particular object to be generated.For example, the control module 810 may determine if a volume of buildmaterial is sufficient to manufacture an object, or if the buildmaterial is of a type which is suitable to produce specified physicalqualities of the object, or the like.

In some examples, the control module 810 of the additive manufacturingapparatus 800 may receive, from the data source, at least one buildmaterial processing parameter. For example, this may specify at leastone temperature or time setting to be used in object generation, or mayspecify at least one print agent for use in object generation. In suchexamples, the control module may control at least one setting of theadditive manufacturing apparatus 800 according to the at least one buildmaterial processing parameter.

In some examples, if the data source is valid and/or the build materialmeets predetermined compatibility criteria, the control module 810 maygenerate a release code, which may for example permit object generationto commence. In other examples, a release code may be supplied from thedata source. Generation of a release code may be dependent on otherparameters. By providing the possibility of authorising an additivemanufacturing apparatus 800 to manufacture an object via a plurality ofinterfaces 802, 804, this increases the flexibility of the systemwithout unduly diminishing security.

The additive manufacturing apparatus 800 may comprise additionalcomponents associated with additive manufacturing, such as energysource, print agent and build material distributors and the like.

In some examples, the control module 810 may write data to a portabledata unit in communication with the second interface. For example, thecontrol module 810 may write data to the data unit to the effect thatthe data unit has been read, and this may result in the ability of thedata source to authenticate or allow object generation processes tocarried out in a manner authorised thereby being revoked, and/orsubsequent validation of the data provided by the data source may berevoked.

Some aspects in the present disclosure can be provided as methods,systems or machine readable instructions, such as any combination ofsoftware, hardware, firmware or the like. Such machine readableinstructions may be included on a computer readable storage medium(including but is not limited to disc storage, CD-ROM, optical storage,etc.) having computer readable program codes therein or thereon.

The present disclosure is described with reference to flow charts and/orblock diagrams of the method, devices and systems according to examplesof the present disclosure. Although the flow diagrams described aboveshow a specific order of execution, the order of execution may differfrom that which is depicted. Blocks described in relation to one flowchart may be combined with those of another flow chart. It shall beunderstood that some flows and/or blocks in the flow charts and/or blockdiagrams, as well as combinations of the flows and/or diagrams in theflow charts and/or block diagrams can be realized by machine readableinstructions.

The machine readable instructions may, for example, be executed by ageneral purpose computer, a special purpose computer, an embeddedprocessor or processors of other programmable data processing devices torealize the functions described in the description and diagrams. Inparticular, a processor or processing apparatus may execute the machinereadable instructions. Thus functional modules of the apparatus (such asthe authentication module 206, data security module 208, control module810 and the like) may be implemented by a processor executing machinereadable instructions stored in a memory, or a processor operating inaccordance with instructions embedded in logic circuitry. The term‘processor’ is to be interpreted broadly to include a CPU, processingunit, ASIC, logic unit, or programmable gate array etc. The methods andfunctional modules may all be performed by a single processor or dividedamongst several processors.

Such machine readable instructions may also be stored in a computerreadable storage that can guide the computer or other programmable dataprocessing devices to operate in a specific mode.

Machine readable instructions may also be loaded onto a computer orother programmable data processing devices, so that the computer orother programmable data processing devices perform a series ofoperations to produce computer-implemented processing, thus theinstructions executed on the computer or other programmable devicesrealize functions specified by flow(s) in the flow charts and/orblock(s) in the block diagrams.

Further, the teachings herein may be implemented in the form of acomputer software product, the computer software product being stored ina storage medium and comprising a plurality of instructions for making acomputer device implement the methods recited in the examples of thepresent disclosure.

While the method, apparatus and related aspects have been described withreference to certain examples, various modifications, changes,omissions, and substitutions can be made without departing from thespirit of the present disclosure. It is intended, therefore, that themethod, apparatus and related aspects be limited by the scope of thefollowing claims and their equivalents. It should be noted that theabove-mentioned examples illustrate rather than limit what is describedherein, and that those skilled in the art will be able to design manyalternative implementations without departing from the scope of theappended claims. Features described in relation to one example may becombined with features of another example.

The word “comprising” does not exclude the presence of elements otherthan those listed in a claim, “a” or “an” does not exclude a plurality,and a single processor or other unit may fulfil the functions of severalunits recited in the claims.

The features of any dependent claim may be combined with the features ofany of the independent claims or other dependent claims.

What is claimed is:
 1. A data unit of an additive manufacturing system, the data unit comprising: a mounting to removably mount the data unit on a receiving portion of an additive manufacturing build material container for containing a source supply of build material; a data source to store data comprising a plurality of additive manufacturing parameters of the build material; and a communications interface to communicate with a reader of an additive manufacturing build material processing apparatus separate from the build material container, wherein the communications interface is to transmit stored data from the data source to the additive manufacturing build material processing apparatus and receive commands to write or change data in the data source; and wherein the data source is organized into data fields, at least one of the fields having a condition that governs use of the at least one field with a condition to prevent use of the additive manufacturing build material container after an unauthorized refilling of the container.
 2. The data unit of claim 1 in which the mounting comprises: a first portion on which the data source and communications interface is mounted, and a registration portion, the registration portion to be received in a corresponding guide portion of the receiving portion of the additive manufacturing build material container.
 3. The data unit of claim 1 wherein the data source comprises a first data field to store a value for an amount of build material remaining in the additive manufacturing build material container, the first data field having a condition that the value in the first data field can only be decremented.
 4. The data unit of claim 1 further comprising an authentication module to provide an authentication response to an authentication request, the authentication response being for communication to the additive manufacturing build material processing apparatus, wherein the data source comprise a first data field to store a key used for authentication, wherein a condition associated with the first data field requires a processing module of the data source to delete or overwrite the key in response to an indication that build material in the additive manufacturing build material container is exhausted.
 5. The data unit of claim 4 in which the authentication module is to receive an authentication request comprising message, to encrypt the message and in which the authentication response comprises the encrypted message.
 6. The data unit of claim 4 in which the authentication module is to authenticate a request from the additive manufacturing build material processing apparatus and, if the request is authenticated, to transmit data from the data source to the additive manufacturing build material processing apparatus.
 7. The data unit of claim 4 in which the authentication response comprises a release code for the additive manufacturing build material processing apparatus, the release code being to authorize at least one additive manufacturing process of an additive manufacturing build material processing apparatus.
 8. The data unit of claim 1 which comprises a processing module of the data source, the processing module of the data source to verify that the condition is met before permitting an associated data field to be overwritten.
 9. The data unit of claim 1 wherein the data source comprises a first data field to store data identifying the additive manufacturing build material processing apparatus authorized to use the additive manufacturing build material container, the first data field having a condition that makes the first data field read-only after an initial write is accepted.
 10. The data unit and additive manufacturing system according to claim 1 further comprising a build material container having the data unit removably mounted thereon and comprising a storage volume to contain additive manufacturing build material; wherein the data source comprises a first data field to store a flag indicating that build material in the storage volume has been exhausted, the first data field having a condition that locks the data field and prevents any overwrite after the flag is set indicating that build material in the storage volume is exhausted.
 11. A method of operating an additive manufacturing system comprising a data unit, the data unit comprising: a mounting to removably mount the data unit on a receiving portion of an additive manufacturing build material container containing a source supply of build material; a data source to store data comprising a plurality of additive manufacturing parameters of the build material; and a communications interface to communicate with a reader of an additive manufacturing build material processing apparatus separate from the build material container, wherein the communications interface is to transmit stored data from the data source to the additive manufacturing build material processing apparatus, the additive manufacturing build material processing apparatus comprising an additive manufacturing apparatus; the method comprising: acquiring, at the additive manufacturing apparatus, the supply of build material for additive manufacturing; removing the data unit from the additive manufacturing build material container; interfacing the communications interface of the data unit with a corresponding interface of the additive manufacturing apparatus; and receiving stored data from the data source to the additive manufacturing apparatus, wherein the data source is organized into data fields, at least one of the fields having a condition that governs use of the at least one field, the at least one field with a condition to prevent use of the build material container after an unauthorized refilling of the container.
 12. A method according to claim 11 further comprising processing the build material by the additive manufacturing apparatus according to the received data.
 13. A method according to claim 11 further comprising determining if the additive manufacturing parameters are available from the data source, the data source comprising a memory of a transfer vessel containing the build material.
 14. A method according to claim 13 further comprising determining another available data source that comprises the additive manufacturing parameters when the additive manufacturing parameters are not available from the data source provided to the reader of the additive manufacturing apparatus.
 15. A method according to claim 11 further comprising validating the additive manufacturing parameters from the data source.
 16. A method according to claim 11 further comprising receiving, from the data source, a build material processing authorization.
 17. A method according to claim 11 further comprising writing, to the data source, an indication that the data thereon has been read.
 18. The data unit and additive manufacturing system of claim 1, further comprising an additive manufacturing apparatus comprising: a first interface and second interface to receive data associated with a build material, wherein the first interface is to receive data from a first data source, and the second interface comprises the reader to receive data from the data source of the data unit; and a control module to control object generation based at least in part on the received data.
 19. The additive manufacturing apparatus of claim 18 in which the control module is to determine which of the first and second interfaces is in communication with an available data source, and to receive data from an available data source.
 20. The additive manufacturing system of claim 1 further comprising an additive manufacturing apparatus having a control module in which the control module is to: prevent at least one operation of the additive manufacturing apparatus in the absence of a release code; validate an available data source; and, if the data source is valid, generate a release code, wherein the release code is conditional on at least one of: an attribute of an object to be formed from the build material, and compatibility of the build material with the additive manufacturing apparatus.
 21. The additive manufacturing apparatus of claim 20 in which the control module is to validate the data source by determining if the data source has previously been accessed by the additive manufacturing apparatus and, if so, determining that the data source is invalid, wherein the data source comprises a first data field to store a flag indicating that data of the data source has been previously accessed. 